Method of making a run resistant stocking tab

ABSTRACT

Fine-gauge, circularly knit seamless stocking has a tab portion of fabric formed after a transfer operation and which represents a terminal portion of knitting. Raveling or runs in the tab portion are prevented by having courses in the tab including a polyamide yarn having a much lower melting point than the yarn used in the remainder of the stocking and which fuses or becomes tacky at boarding temperature so that the fusing takes place during this stage of processing.

United States Patent [191 Millar 1451 Mar. 12, 1974 METHOD OF MAKING ARUN RESISTANT STOCKING TAB X U A 9 m U 6 L a e d n a r. F

Conner Nebel Currier Pons et al.

[75] Inventor: John J. Millar, Laconia, NH.

[73] Assignee: Scott & Williams, Inc., Laconia,

4/1967 Czechoslovakia.................66/178 [22] Filed: June 3, 1971Appl. No.: 149,451

Related US. Application Data Division of Ser. No. 13,700, Feb, 24, 1970,Pat. No. 3,61 1,755, which is a continuation-in-part of Ser. No.765,821, Oct. 8, 1968, abandoned. Y i

-. Primary Examiner-Wm. Carter Reynolds McNenny, Farrington,

Attorney, Agent, or Firm- Pearne & Gordon ABSTRACT b a t a S a h g .m kC o t S s S .n m a e S an n k N r h u C .H C e g u a m m 1 P 66/95,66/136, 66/173, 260/78 A, 260/78 L D04b 9/54, D04b 9/56 Int.

portion of fabric formed after a'transfer operation and which representsa terminal portion of knitting. Raveling or runs in the tab portion areprevented by having courses in the tab including a polyamide yarn havinga 3 5 H ,8 22 0.1 L RR n a A 100 A ww 2 7 66 63 .1 m l W 6 e S f 0 d l ei F l 00 5 1 [56] References Cited much lower melting point than theyarnused in the UNITED STATES PATENTS remainder of the stocking and whichfuses or becomes tacky at boarding temperature so that the fusing takesplace during this stage of processing.

my 0 m w n we BK 386 445 999 NH 85 2 Claims, 4 Drawing Figures METHOD OFMAKING A RUN RESISTANT STOCKING TAB RELATED CASE This application is adivisional application of application Ser. No. 13,700, filed Feb. 24,1970, now US. Pat. No. 3,611,755, which is a continuation-in-part of mycopending application, Ser. No. 765,821, filed Oct. 8, 1968, nowabandoned.

This invention relates generally to seamless circularly knit hosiery andmore particularly to hosiery which is knit in such a manner that atransfer operation of loops from the dial to the needles is performed atthe end of the knitting operation and a tab formed of a number ofcourses knit after the transfer operation and before it is pressed off.

Stockings are formed with a tab portion knit after a transfer operationeither when the stocking has been knit in the reverse direction and anin-turned welt formed after knitting the body of the stocking or whenthe stocking is knit in the usual direction so that the toe is formedlast, then a tab is formed after a transfer operation when the toe isclosed on the knitting machine by constricting a double layer of fabricat the toe.

A particular problem in such a tab is that since it is formedimmediately before press-off, the loops tend to be free to run and theyarn ends are subject to raveling even though the tab may be knit with arun-resistant stitch pattern and may naturally tendto curl. up so thatthe terminal courses are protected,

One method of preventing raveling or running in the tab was disclosed inthe prior patent applications of John J. Millar, Ser. No. 680,226, filedNov. 2, 1967, now abandoned, and Ser. No. 703,949, filed Feb. 8, 1968,now U.S. Pat. No. 3,488,981, granted Jan. 13, 1970. According to thedisclosure in these applications, the tab was sealed on the knittingmachine by means of an electrically heated element which was broughtinto close contact with the tab during the knitting of the finalcourses. This allowed the heat to fuse the thermoplastic yarns fromwhich the stocking was knit and after the stocking was pressed off andprior to finishing, the last knit courses were separated from the firstknit courses of the tab at the fused zone so that after removal of thisring of material, the exposed yarn ends were fused together in such amanner that raveling or running was substantially eliminated.

The foregoing method of sealing the tab, while providing a substantiallyrun-proof tab, has been found to have certain drawbacks, such asrequiring the presence of a special electrically heated element, theelectrical circuitry to operate the element, and additional controls onthe knitting machine to bring the element into operation in the desiredmanner. This has been found to substantially increase the cost of theknitting machine as well as to increase the maintenance needed becauseof the tendency of the hot wire to pick up fused material from thestocking which tends to carbonize on the filament, which then requiresperiodic cleaning. Still another problem with this method has been thedifficulty in obtaining consistent and proper bonding of the material.If the yarns used in the fused area are a conventional nylon, there issome difficulty in restricting the fusion to the desired zone withoutthe heat causing damage to proximate areas other than those where thebonding is desired. As mentioned in the aforesaid US Pat. No. 3,488,981,efforts have been made to utilize a yarn made of a material having alower melting point than that of the nylon used in the rest of thestocking, and using this lower melting point yarn in the structure ofthe tab, so that upon operation of the heated element, the temperatureresulting in the fabric will. be sufficient to melt the low meltingpoint yarn but insufficient to damage the nylon yarns, so that only thelow melting point yarn is melted and caused to bond to the backing nylonyarns to cause them to adhere together in such a manner as to produce arun resistant structure.

The use of a different yarn in the tab structure has another drawbackbecause of the difference of the'physical properties of the yarn fromthat of the nylon. The use of material such as polypropylene and variousvinyl and vinyl type yarns has caused the presence in the tab of amaterial having a substantially lower tensile strength than that of thenylon structure. Since the tab may be in a location such as at the weltof the stocking where it is subject to continual stretching, suchrepeated stretching action on the bonded courses of the tab may, becauseof the different tensile strength of the nylon and low melting pointnon-nylon components, cause the latter to break and rupture, therebydestroying the bondingaction which has produced the runresistantstructure. This problem is further accentuated by the fact that suchlow-melting point yarns are not truly compatible with nylon in that whenthey fuse they merely cause a surface adhesion to the nylon at theinterface which may not produce a sufficiently strong bond to preventrupture when the fabric in this area is stretched. With melt compatibleyarns, the interface substantially disappears or becomes indistinct andthe juxtaposed threads actually fuse or blend together at their contactpoints to form a solid solution of the difv ferentially melting nylonyarns.

An important feature of the present invention is that it allows coursesin the tab to be fused together after the stocking has been completelyknit and removed from the knitting machine.

Another important feature of this invention is that the fusing can takeplace during the usual boarding, dying or other finishing operations onthe stocking where the stocking is placed on a form and exposed tosaturated steam at a temperature to set the stocking to the desiredshape.

Another feature of this invention is that it reduces the number ofcourses in the tab while retaining a sufficient degree of fusion toprevent raveling and running.

Still another feature of this invention is that it is adaptable tomachines having different numbers of feeds, may be used in combinationwith various run resist structures and requires no special modificationof the knitting machine to adapt the invention to existing machines inwhich the tab is already formed.

Briefly, the foregoing features of this invention are realized in thepreferred embodiment where the body of the stocking is knit with theconventional nylon 66 or nylon 6 yarns. When the tab portion is knit, aspecial yarn is introduced at at least one of the feeds of the machineand fed together in random plated relationship with a backing yarn ofthe same type used in the remainder of the stocking. The knitting may bedone using a run resistant structure for several courses after which thestocking may be pressed off. The special yarn is a low melting pointnylon yarn which fuses at normal boarding temperatures so that when thestocking is processed in the normal manner and boarded, the heat of theboarding process will be sufficient to melt the low melting point yarnto a sufficient degree to cause it to adhereto its backing yarn and theyarns contacting it at various points in the knitted structure. Afterthe boarding process has been completed and the stocking cooled, the lowmelting point yarn will thus be fused or caused to adhere to the otheryarns in such a manner that no raveling or running can take place.

Thus, the fused tab is provided without special processing on theknitting machine or any separate machine and the fusing is completedduring the finishing operations on the stocking. Further features andadvantages of the invention will readily become apparent to thoseskilled in the art upon a more complete under-' standing of theinvention as set forth in the accompanying detailed description and inthe figures in which:

FIG. 1 is a diagramatic elevation of a stocking incorporating thepresent invention;

FIG. 2 is an enlarged fragmentary cross-section of the welt structureincluding the tab of the stocking shown in FIG. 1;

FIG. 3 is an enlarged fragmentary view of the toe of a stocking in whichthe toe includes a tab formedafter transfer; and g I FIG. 4 is a fabricdiagram showing a preferred stitch structure for the tab coursesaccording to the present invention.

Referring to the figures in greater detail, FIG. 1 shows a stocking towhich this invention is particularly applicable. Heretofore, ladiesfine-gauge hosiery has been generally knit starting from the welt, whichwas usually formed with an inturned welt, down the leg, through the heeland into the toe which was generally finished with a reciprocated toepocket with a number of courses of a yarn which was ofa low cost varietyand which was removed from the stockings during the finishing operationswhere the toe was closed by stitching or looping.

However, with the development of methods of closing the toe on theknitting machine, such as disclosed in the patents of John A. Currier,US. Pat. No. 3,327,500 issued June 27, I967, reissued May I3, 1969 asRe. 26,581, US. Pat. No. 3,340,706, issued Sept. l2, l967, reissued May13, 1969 as Re. 26,580, and U.S. Pat. No. 3,340,707 issued Sept. I2,1967, a problem has arisen upon termination of knitting and press-offbecause the terminal courses remain in the finished stocking. When thestocking is knit toe first according to the preferred method of closingthe toe on the knitting machine, the inturned welt is formed last andafter knitting the welt fabric and performing the necessary transferoperation, it is necessary to terminate knitting in such a manner as toprevent the possibility of runs or raveling on the exposed edge offabric.

Thus, as shown in FIG. 1, a stocking when knit in the reverse directionis formed first with the closed toe 12 and then knit in a direction upthe leg from the foot 11 and terminates in an inturned welt indicatedgenerally at 14. As shown in greater detail in FIG. 2, the inturned weltconsists of an outer layer of fabric 15 which is continuous with thebody portion of the stocking and an inner layer of fabric 16 which iscontinuous with the layer 15 but has been folded over to form the doublefabric layer. The layers 15 and 16 are joined together at the transfercourses indicated at 18 with interlocked courses as described in greaterdetail in the aforementioned Currier patents. After the transfer hastaken place, additional courses are knitted to form annular portion offabric, generally called a tab, shown at 20, which represents the lastfabric knit prior to press-off and which must form a barrier to preventraveling and running into the interlocked courses 18 or further backalong the fabric of the stocking.

When the stocking is knit in the opposite direction, the inturned weltis formed first and the closed toe formed during the final portion ofknitting the stocking, and a tab is also formed at the inside of the toeof the stocking as indicated in FIG. 3. In such case, the toe' is formedwith an outer fabriclayer 22 and an inner fabric layer 23 which whileconstricted together atthe end to form the closed toe are joinedtogether with interlocked transfer courses at 26. Thus, after thisoperation has taken place there remains a tab portion 27- similar instructure to the tab 20 to prevent running and raveling in the toe area.Thus, regardless of the direction in which the stocking is knit, thereremains a tab portion formed after the last transfer operation and priorto press-off which must act as a barrier to prevent runs and ravelsstarting and continuing into the remainder of the stocking.

g It has been recognized in the aforementioned patents of Currier andthe aforementioned patent applications of Millar that when the knittedtab is allowed to relax it has a tendency to curl upon itself as shownin FIG. 2. While this gives some protection to the very terminal coursesof the tab, it is not sufficient because of the tendency of the tab tounroll both when tension is applied by lateral stretching and underphysical contact when the stocking is worn. While some protectionagainst raveling and running is formed by knitting so-calledrun-resistant stitches in the tab, it has been recognized as desirableto provide additional protection, particularly when the tab appears atthe welt. Because of the thermoplastic nature of the nylon or polyamidetype fiber-which is used today for substantially all the production offine-gauge ladies hosiery, it has been proposed to cause some fusion ofthe fiber so that adjacent fibers bond together in such a manner thatthe yarns are locked and cannot run or ravel. In the aforementionedMillar US. Pat. No. 3,488,981, the area of the tab fabric was fused bythe application of heat through an incandescent wire, and while thisproduces a fusion which is able to positively prevent runs and ravels,it increases the cycle time of the knitting machine and requires aseparate operation because the additional portion of the tab must beremoved outward of the fused portions because the heat cannot be appliedtoo close to the needle circle, and also produces a longer tab than isdesired to insure that the heat is kept away from the transfer courses,where any weakening of the yarn by heatwould immediately cause a breakwhich would allow runs to appear almost at once.

According to the present invention, a much smaller and yet highlyrun-resistant tab can be produced without requiring any specialoperation either on the knitting machine or during the finishingprocesses nor is any modification of the finishing processes requiredfrom those generally in use. Generally, this is accomplished by knittinga tab structure after the transfer courses in which is incorporated ayarn which melts or fuses to a sufficient extent during the boardingprocess at temperatures generally between 240 to 260 F to bond itself tothe other yarns and produce an almost runproof structure. Under theseconditions, the low melting point yarn is knit with a standard nylonbacking yarn in a plated relationship to maintain the continuity of allloops in the tab structure. If a sufficient amount of the low meltingpoint yarn is used and fusion allowed to take place for a sufficienttime, then additional bonding takes place in addition to the fusion atthe yarn junctions so that the folded or curled layers of fabric in thetab as shown at 20 in FIG. 2, will tend to bond themselves to each otherso the tab can no longer uncurl even when stretching is relaxed and thisprovides additional positive sealing of the tab against raveling orvruns.

The low melting point yarn used in this tab structure is necessarily apolyamide or copolyamide to insure the best possible bonding to theregular nylon (polyamide) yarns. There materials also have similardyeing properties so that after the dyeing operation they will appearsubstantially the same asthe conventional nylon'yarns used in theremainder of the stocking.

The best yarns are copolyamides which are fiberforming and which have amelting point within the range of from about 115 to about 140C.Generally, such low melting point fiber-forming polyamide yarns areformed by known methods from amino acid or lactam materials, one ofwhich contains relatively fewer carbon atoms than the other. Thesematerials are reacted in ratios which vary from 20 to 80 parts of thelow carbon atom amino acid or lactam to from 80 to 20 parts of the highcarbon atomamino acid or lactam. A preferred range of ratios of suchamino acid or lactam materials is from 40 to 60 parts of the lo'wcarbonatom material to from 60 to 40 parts of the high carbon atom material.

The low carbon atom amino acids or lactams generally contain six toeight carbon atoms. The high carbon atom amino acids or lactamsgenerally contain from ,to or more carbon atoms.

Specific examples of the low carbon atom amino acids or lactams includeomega-amino caproic acid or caprolactam, omega-amino caprylic acid orcaprylolactam, 6-amino-2-ethyl hexanoic acid, 4-aminohexahydro benzoicacid. Specific examples of the higher carbon atom amino acids or lactamsinclude omega-amino decanoic acid, omega-amino undecanoic acid,N-methylamino-undecanoic acid, omega-amino lauric acid or laurolactam,omega-amino pentadecanoic acid.

These materials may be reacted in various ratios to yield fiber-formingnylon type polyamides or copolyamides which have a melting point betweenabout 115 and 140C. The polymerization procedure is conventional andreference may, be had, for an example, to Rowland Hill, Fibers fromSynthetic Polymers, Elsevier (1953), Pages 132-133.

In general, these copolyamides have molecular weights between about15,000 and about 20,000. Specific examples of useful copolyamides havingthe desired properties within the ranges aforesaid include a copolyamideof caprolactam and omega-amino decanoic acid (50:50), a copolyamideofcaprolactam andomega-amino undecanoic acid (40:60), a copolyamide ofcaprylolactam and omega-amino decanoic acid (50:50), a copolyamide ofcaprolactam and omegaamino lauric acid (55:45), a copolyamide ofcaprolactam and omega-amino decanoic acid (40:60), a copolyamide ofomega-amino undecanoic acid and N- methylamino-undecanoic acid (55:45),and the like.

Yarns formed by conventional spinning procedures are preferably used ina 40 denier 9 filament strand having a tensile strength between 5 and 6grams per denier and a melting peak between about to about C so thatsubstantially complete melting and fusing of the fiber takes place atboarding temperatures between 240 and 280F, preferably between 240 and260F. Of course, other yarns can be used if they have a melting orfusing temperature within this range and such yarns should be preferablyof the polyamide, polyester or mixed polyamide-polyester type to providethe requisite high degree of bonding with the basic nylon fiber used inthe remainder of the stocking and have a sufficiently high tensilestrength that the stocking is not weakened in the areas of bonding.Since the extremes of boarding temperatures range between 220 and 270Fand all polyamide materials normally used in hosiery have a meltingpoint above 350F there is no fusing or bonding of the nylon yarns in theremainder of the stocking during boarding.

The tab structure which includes the low melting point yarn ispreferably knit with a run resistant structure to provide a maximumamount of contact between adjacent yarns while maintaining a high degreeof stretchability, both before and after fusion has taken place. Apreferred structure for this purpose is shown in FIG. 4 where thenumbers 1,2,3, and 4 indicate the position of adjacent needles on theneedle cylinderon two feeds. On one revolution as indicated at D, the

first feed knits a normal nylon type 66 stretch yarn 30 of about 30denier on all the needles, although as shown in the fabric diagram, theloops taken on alternate needles become degenerate after completion ofthe stitch structure and therefore show no loops in the finished fabric.However,.because there wer originally loops on every needle with thisyarn, the considerable bulk of this yarn allows considerable stretch.Since this yarn is subsequently bonded only at its junctions with thelow melting point yarn, it is free to provide a considerable amount ofstretch.

On the same revolution as indicated at C, at the second feed twoyarnsare knit together. These yarns consist of, for example, a 15 deniernylon 66 monofilament backing yarn 31 together with the low meltingpoint yarn 32 described above at about a weight of 40 denier. Theseyarns are fed together to provide a random plated arrangement withoutregard to which surface either yarn is exposed at. This backing yarn ofa conventional type 66 nylon is used since it will not substantiallysoften at the boarding temperature and there fore provides loopcontinuity and backing support for the fusible low melting point yarn.This yarn is knit on alternate needles such as l and 3 on one coursewhile the intervening needles 2 and 4 tuck and on the subsequentrevolution of the needle cylinder selection is reversed so that needles2 and 4 knit while needles 1 and 3 tuck. I v

This arrangement of continual knitting on all needles at the first feedstation and alternate knit and tuck structures at the second feedstation alternating between each revolution of the machine provide astruc- It is recognized that other stitch structures can be used and aplain knit can be used using the low melting yarn in plated relationshipwith a backing yarn either at every feed station so that it appears inevery course or on spaced courses with intervening courses which arenotfused by the low melting point yarn. It is recognized that if the lowmelting point yarn appears on all courses, a more effective anti-rave]and run resist structure is obtained at some loss in the stretchabilityof the fabric, and therefore by balancing the structure the propercombination of stretchability and run resistant structure can beobtained. If the low melting point yarn is introduced immediately aftertransfer, a minimum number of courses in the tab are required to producea completely run resistant structure after the fusingand bonding hastaken place during the boarding operation. It is desirable to have atleast eight courses of this structure to provide the maximum amount ofrun resistance, but if it is desired to increase the stretchability andreduce the bulk of the fabric a fewer number of courses may be used ifdesired.

Regardless of the actual knitted structure used in the tab, the use ofthe low melting point nylon which is fused to the higher melting pointnylon produces a strong run-resist structure because the nylon yarns,being compatible with each other, cause a thorough fusion rather thanmere surface bonding as occurs if a non-polyamide material is used inthe tab. In addition, such low melting point nylon yarns will tend to besimilar in appearance, feel and dying properties to the nylon used inthe rest of the stocking, so that they will not become readily apparenteither visually or by feel. Likewise, because the low melting pointnylon has similar physical characteristics of tensile strength andelongation with standard nylon yarns, it will retain the same degree ofphysical durability and have the same strength so that they will nottend to break or rupture during handling any more than that of the nylonyarns used in the tab and the remainder of the stocking.

What is claimed is:

1. A method of forming, on a knitting machine having a plurality ofneedles and transfer instrumentalities, a run resistant tab portion on'anylon stocking having the tab portion knit after a transfer operationand just prior to press-ofi comprising knitting said tab portion toinclude in at least one course two yarns in plated relationshipthroughout the course, both of said yarns being nylon, one of said yarnsbeing a nylon having a melting point above 350F, and the other of saidyarns being of a nylon having a melting point between 240 and 280F,removing the stocking from the knitting machine, and thereaftersubjecting the stocking to a boarding operation at a temperature between220 and 270F whereby the yarn having a lower melting point is fused tothe yarn having the higher melting point to provide a run resistantstructure.

2. A method of forming a run-resistant section of a stocking on aknitting machine having a plurality of needles and transferinstrumentalities comprising the steps-of knitting said stocking sectionwith said needles to include in at least one course one polyamide yarnhaving a melting or fusing point between 240 and 280F, said one yarnbeing knit in plated relationship throughout the course with a secondpolyamide yarn having a melting point above 350F, removing the stockingfrom the machine and thereafter subjecting the stocking to a finishingoperation at a temperature between 220 and 270F to fuse said one yarn.

1. A method of forming, on a knitting machine having a plurality ofneedles and transfer instrumentalities, a run resistant tab portion on anylon stocking having the tab portion knit after a transfer operationand just prior to press-off comprising knitting said tab portion toinclude in at least one course two yarns in plated relationshipthroughout the course, both of said yarns being nylon, one of said yarnsbeing a nylon having a melting point above 350*F, and the other of saidyarns being of a nylon having a melting point between 240* and 280*F,removing the stocking from the knitting machine, and thereaftersubjecting the stocking to a boarding operation at a temperature between220* and 270*F whereby the yarn having a lower melting point is fused tothe yarn having the higher melting point to provide a run resistantstructure.
 2. A method of forming a run-resistant section of a stockingon a knitting machine having a plurality of needles and transferinstrumentalities comprising the steps of knitting said stocking sectionwith said needles to include in at least one course one polyamide yarnhaving a melting or fusing point between 240* and 280*F, said one yarnbeing knit in plated relationship throughout the course with a secondpolyamide yarn having a melting point above 350*F, removing the stockingfrom the machine and thereafter subjecting the stocking to a finishingoperation at a temperature between 220* and 270*F to fuse said one yarn.